In many agricultural crops such as corn, devastating pests tend to feed on vegetative tissues such as the leaf, stalk and root and also reproductive tissues such as the ear. One technique used to protect plants from pests is the application of chemical compounds. An alternative technique involves genetic recombination, wherein a gene or genes are introduced into the plant to express protein products that are directly or indirectly involved in the control of the pest organisms. Current protein products produced by genetic recombination are expressed constitutively, i.e., throughout the plant at all times and in most tissues and organs. Such protein products are also expressed specifically, either in response to particular stimuli or confined to specific cells or tissues. In contrast, the present invention includes expression of the protein or polynucleotide of interest in basically all plant tissues, but essentially excludes expression in the tissues of the reproductive structures of the plant, particularly in the tissues of the pollen and/or the tassel so that no expression product is present in said tissues to any significant extent.
Several insect control trait genes target the larval stage of development. Under certain circumstances, these proteins also affect unintended insects, which are not corn pests, but do occasionally feed on corn pollen. These insects may be harmed by insecticidal proteins expressed in pollen tissue. This was seen as a problem in early BT-corn events which had high insecticidal protein expression in pollen. This issue was addressed in later BT-corn events through the development of alternative transgene expression systems. These newer events remained effective against target pests and accumulated less insecticidal protein in pollen, but are still viewed as potentially harmful to non-target pests due to the presence of insecticidal protein in pollen.
In some instances, useful insect control trait genes may also compromise the development of reproductive structures of the plant such as, for example, the tassel.
It is, therefore, desirable to provide plants, particularly corn plants that exclude expression of the transgene in the tissues of the reproductive structures of the plant such as the tissues of the pollen and/or the tassel. This could be achieved within the scope of the present invention by providing a regulatory nucleotide sequence, at least part of which has a transcription initiation function directing expression of an operably associated protein encoding a polynucleotide of interest to basically all plant tissues, but essentially excluding expression in the tissues of the male reproductive structures of the plant, particularly in the tissues of the pollen and/or the tassel so that no expression product is present in said tissues to any significant extent. This regulatory nucleotide sequence can then be used to develop expression systems that enable effective accumulation of the polypeptide or protein of interest such as, for example, an insecticidal protein, in tissues that target pests normally feed on, and eliminate or reduce accumulation of the insecticidal protein in non-target tissues or organs and/or in those tissues that may be compromised by the polypeptide or protein of interest.